1. Field of the Invention
The present invention relates to surgical procedures and, more specifically, to minimally invasive procedures for surgery involving portions of the heart and great vessels located between a point approximately 3 centimeters above the supra annular ridge and the mid-ventricular cavity, such as, for example, procedures for repair and replacement of the aortic valve.
2. Description of the Related Art
Various types of surgical procedures are performed on the heart and the great vessels. Many of such procedures, particularly those involving the aorta, and aortic valve employ a gross thoracotomy, e.g., a median sternotomy, in order to gain access to the involved portion of the heart or vessel. In other words, the procedures entail splitting open the patient's chest. Such procedures cause significant trauma to the patient, and recovery time.
An example is the conventional procedure for aortic valve surgery. The patient is anesthetized, and the skin is incised from the top of the sternum to a point located a predetermined distance, e.g., approximately two inches, below the bottom of the sternum. The sternum is then split longitudinally, using a saw or other cutting implement. A spreader is placed within the chest cavity and the opposing halves of the rib cage spread apart to expose the thoracic cavity. The tissues around the heart are divided, opening the pericardial sack. A cardiopulmonary bypass is initiated through direct aortic and right atrial cannulation (that is, circulation to a heart-lung machine is established through an arterial-returning catheter disposed in the aorta and a venous drainage catheter in the right atrium); the aorta is clamped (typically between the brachycephalic artery and the coronary ostia) to exclude the heart from the circulation. The cardiac function is then arrested, i.e., the heart is stopped by infusion of a cardioplegia fluid, such as a cold potassium solution. The aorta is then opened. The valve is then repaired, or if to be replaced, excised and a replacement valve sewn in. Any air that may have accumulated in the heart during the procedure is then removed from the heart and the aorta closed with sutures. The clamp is then removed, patient weaned from the heart-lung machine, tubes removed from the aorta, the sternum wired back together and the skin closed with sutures.
Such procedures are particularly traumatic. Incisional pain tends to require significant postoperative analgesia and postoperative discomfort tends to result in significant patient morbidity and lengthy hospital stays. In addition, because the pericardial sack is opened underlying the sternum, after the procedure the heart has a tendency to become adherent to the sternum. This can be problematical in the event of subsequent procedures.
The desirability of avoiding the use of median sternotomy, and other gross thoracotomy procedures, in connection with surgery on the heart and the great vessels has been recognized. For example, techniques have been proposed in which a scope is inserted through a percutaneous intercostal penetration in the patient's chest (an incision between the ribs) to observe internal procedures performed by instruments introduced into the chest with the scope, or through cannula disposed in other intercostal spaces, i.e., between two adjacent ribs. Such techniques and instruments for performing such techniques within the heart and great vessels is described in International Publication WO 95/15715 by Sterman, et al., published Jun. 15, 1995. However, such techniques require special instrumentation and special skills to perform, and may extend the time the heart is arrested and the duration of the procedure.